Electronic device



May 2, 1939- H. F. DALPAYRAT ELECTRONIC DEVICE Filed April 25, 1934 IHVEHTOR BY Henri F'rancoisDalpayrat ATTORNEY Patented May 2, 1939 ore s ELECTRONIC DEVICE Henri Francois Dalpayrat, New York, N. Y., assignor, by mcsne assignments, to Radio Corporation of America, a corporation of Delaware Application April 25, 1934, Serial No. 722,235

5 Claims.

My invention relates to improvements in electronic devices and means for operating such devices, and more particularly to an electron discharge tube with a novel control element and method of controlling the electron current in accordance with input signalling current or po tential variations.

In the known electron tubes in the art comprising substantially a cathode, an anode and a grid mounted in a vacuous space, the grid acts substantially by producing an electrostatic field in the path of the electron stream tending to obstruct more or less the electron flow and correspondingly varying the current in an output circuit in which the electron path is included.

Serious disadvantages are experienced with this type of tube utilizing the electrostatic eiTect of the grid on the electron current due primarily to the action of inter-electrode capacity, especially the grid-anode capacity. This causes. undesired reaction of the output current upon the input, resulting in signal distortion and the production of oscillations causing interfering noises and whistling notes, etc., as is Well known. Various means have been proposed to overcome this internal retroaction known as capacitative interelectrode feedback such as, the use of neutrodyne circuits, screen grid tubes, etc. All these means become less effective as the frequency increases, and great difficulties are still experienced in designing amplifiers for very high frequencies, such as required in short wave and ultra-short wave work.

Accordingly, it is an object of my invention to provide a new electron discharge device with a novel controlling element and mode of control in which reaction from the output to the input is substantially eliminated.

Another object of my invention consists in the provision of a novel electronic control device which is especially adapted for use in short wave and ultra-short wave signalling systems such as broadcast receivers, transmitters, and the like.

A further disadvantage in electron tubes of the type heretofore known in the art is the fact that considerable distortion of the output current variations may occur, caused by grid currents if the grid is made positive during the positive half cycles of the grid controlling potential.

Accordingly, it is a further object of my invention to provide a new electron tube construction in which a flow of current in the grid or controlling circuit is substantially eliminated.

' Another disadvantage in electron tubes of known design using an electrostatic control grid is the fact that when exceeding the straight line portion of the operating characteristic of the tube, that is, the range of the space charge effect, substantial distortion of the anode current variations will occur due to saturation, thus greatly limiting the operating range and the efiiciency of devices of this type.

Accordingly, it is another further object of my invention to provide a new vacuum tube construction in which the discharge current is main-- tained at maximum or saturation flow at all times, thus substantially eliminating the defects and drawbacks inherent in vacuum discharge devices as heretofore known due primarily to the space charge efiect and saturation phenomena of the discharge current.

A further drawback inherent in electron discharge tubes of usual design is due to the emission of secondary electrons by the anode electrode especially when heavy discharge currents are desired, causing objectionable interference with the operation of the tube as well as .de-

creasing its efficiency as to undistorted output power and setting up disturbing tube noises mainly caused by the secondary electrons striking the grid electrode. It has been suggested to overcome this drawback, such as. by the use of a special suppressor grid and the like, all of these means more or less complicating the construction of the tube and causing other undesired interference during operation.

It is therefore a further object of my invention to provide novel means in connection with an electron discharge device for controlling the discharge current in accordance with input signals by which the effect of secondary electrons on the discharge current is eliminated, resulting in greatly increased efficiency with regard to undistorted power output.

These as well as further objects and aspects of my invention will become more apparent from the following detailed description taken in reference to the accompanying drawing in which I have illustrated by way of example the novel tube construction and circuit arrangements for utilizing same in accordance with the invention.-

I wish it to be understood, however, that the drawing is to be regarded only as being illustrative of the novel principles and underlying features of my invention which, as will become obvious, is susceptible to various modifications and variations coming within its broader scope and spirit as expressed by the appended claims.

Figure 1 illustrates an electron discharge tube with a novel control arrangement in accordance with the invention.

Figure 2 shows a radio receiving circuit embodying tubes of the type as shown by Figure 1.

Figure 3 illustrates a modification of using a tube according to the invention for receiving radio signals.

Figure 4 is a further modification of a receiving tube according to the invention operating according to the push-pull principle.

Figure 5 is a partial view showing an auxiliary anode of special construction as used in a circuit shown by Figure 4.

Similar reference numerals identify similar parts throughout the different views of the drawing.

Principally the invention contemplates the use of an electronic discharge device comprising substantially a source of electrons such as a thermionic cathode, a cooperating positive electrode arranged in an evacuated space, and means for concentrating the electron discharge current of the cathode into a sharp pencil or beam directed towards the anode and for varying the degree of concentration or diffusion of the electron pencil or beam in such a manner that with a given geometric design of the anode electrode an electron beam of varying density strikes the anode, resulting in a corresponding variation of the current in the output circuit including the concentrated electron path between said cathode and anode.

Referring more particularly to Figure 1 of the drawing, I have shown an electron discharge device in accordance with the invention comprising mounted, upon a base 2 and provided with an towards the positive or anode-electrode I.

inwardly projecting stem or press 8 which serves as a mounting means for the electrodes within the tube. The tube is preferably of the highly evacuated type but it is understood that it is also possible to use a gaseous filling of specific nature Without departing from the principle and spirit of the invention. Mounted within the bulb l is a set of electrodes comprising a cathode 3 which may be a thermionic cathode of known construction in the form of either a straight horizontal wire or a V-shaped type cathode comprising a wire passing backward and forward in a zigzag fashion, as is well known in the art. The

cathode may be mounted by well known mounting means such as mounting rods fixedly sealed in the press 8 of the tube, as indicated in the drawing. The terminals of the cathode are connected to a pair of prongs 3 arranged at the base of the tube for applying a heating current to heat the cathode to electron emitting temperature. Alternatively, an indirectly heated cathode of the heater type known in the art may be used in place of a direct heated filament as shown in the drawing.

I have furthermore shown a plate-like electrode 5 mounted underneath the cathode 3 normally having a negative potential applied to it and acting as a baffle or reflecting element to project the electron beam emitted by the cathode The electrode 5 maybe mounted by well known means and is connected to a connecting prong 5 at the bottom of the base 2. It is also possible to omit the reflecting electrode 5 in order to secure satisfactory results.

Numeral 4 represents a. cylindrical shaped electrode substantially surrounding the cathode 3 and acting as a concentration cylinder for focusing the electron emission current supplied by the cathode 3 into a sharp pencil or beam in the direction of the anode I. For this purpose the cylinder 4 has a negative potential applied to it in accordance with well known arrangements similar to the construction of cathode ray tubes used for oscillographic purposes and in scanning systems for television transmission and reception. The anode l is connected to a cap terminal I mounted on the top of the tube. I have furthermore shown an additional positive or plate electrode 6 arranged in front of the anode I and having a central opening or passageway through which the pencil or beam of electrons passes towards the anode 1. Cylinder 4 and plate 6 are connected respectively to prongs 4' and 6 in a similar manner as the other electrodes as shown.

The effect of the concentrating cylinder 4 on the electron stream is similar to an optical lens system used for focusing or diffusing a beam of light in an optical system. The electrical equiva- H lent to the optical characteristics, such as focal length, lens curvature, etc., is substantially represented by the geometrical dimensions of the cylinder 4 on the one hand and the electrical po tential applied to it on the other hand, in such a manner that with a given electrode construction it is possible by varying the potential applied to the cylinder 4 serving as the controlling element to vary the concentration or diffusion of the electron pencil, or, in other words, the density of the electron beam striking the surface of the anode 7 resulting in a corresponding variation of the current in the anode output circuit.

Thus, assuming for instance a negative potential of sufiicient value to be applied to the cylinder 4 in such a manner that the electron pencil produced has a cross-section substantially equal to the cross-section of the perforation in the auxiliary anode 6, it is readily seen that density of the electron beam striking the anode I is such that substantially all of the electrons emitted by the cathode are collected by the anode, resulting in maximum current flow in the connected output circuit. If now by decreasing the negative potential applied to the cylinder 4, the electron pencil is diffused or its cross-section increased, only part of the diffused electron beam will strike the anode 7 due to the decreased electron density while the remaining portions of the electron pencil will be impinged upon the auxiliary anode 6, setting up a current in the circuit connected thereto. It is readily seen that the currents in the circuits connected to the anode 1 and to the auxiliary anode 6 are of opposite phase; that is, while the current collected by the anode 1 increases, the current in the circuit connected to the auxiliary anode 6 decreases.

It is also seen that in a device according to the invention, the emission current may be adjusted to maximum or saturation value; that is, the op eration takes place outside the range of the space charge effect, resulting in increased efficiency and freedom from disadvantages caused by a space charge.

An electronic control device as hereinbefore described lends itself to various uses in connection with electrical circuits, in particular for reception of radio signals for amplifying, modulating, or demodulating signals, and for various other functions.

Referring to Figure 2 of the drawing, I have shown, for the sake of illustration, a radio receiving circuit utilizing tubes of my novel construction and comprising a radio frequency amplifier, combined detector and first audio amplifier and second audio power amplifier stage operating a loud speaker or other receiving device.

The circuit shown by Figure 2 comprises an antenna ground system shown at 9 for collecting incoming radio waves. The antenna circuit is coupled to the input circuit of a high frequency amplifier tube l2 through a high frequency transformer [0 which may be tuned to the incoming frequency by means of a variable condenser H shunted across the secondary of the transformer Ill.

The thus received signals are applied to the input of the tube l2 across a condenser 2i and leak resistance 22 connected to the controlling element or concentration cylinder l5 of the tube in a manner similar to receiving circuits utilizing ordinary vacuum tubes with electrostatic grid control. The tube [2 includes a further electrode system similar to Figure 1 comprising a cathode H, a negative reflecting plate It mounted underneath the cathode, an auxiliary anode l9 and a main anode IS. The filament ll may be supplied with heating current in any known manner (not shown in the drawing for the sake of better illustration and normally is placed at ground or negative potential similar to the well known radio circuits).

I have furthermore shown a source of current such as battery 23 for applying a negative biasing potential to the concentration cylinder or control element l5 and a further source of potential 24 for applying a negative bias to the refleeting plate 56 of the tube. Numeral 25 represents a source of potential for supplying the positive voltage for both the main anode and auxiliary anode l8 and I9, respectively. Included in the circuit of the source 25 is an output transformer 26 which serves to couple the tube l2 to the succeeding stage.

In the arrangement shown, the auxiliary anode l9 serves as the output electrode while the anode I8 is used for producing additional amplification through regeneration by being connected through a feedback or tickler coil 20 to a point of proper positive potential on the operating source 25. Since the current variations in the circuit connected to the anode iii are of opposite sense to the variations in the auxiliary anode 89, it is necessary to properly connect the feedback coil so as to insure proper phase of the signal variations fed back into input circuit for producing either regeneration or degeneration of the signalling current variations, as desired.

While I have shown separate batteries for biasing the different electrodes, it is understood that a single battery with proper potentiometer arrangements may be provided for producing proper operating potentials as is well known in the art of vacuum tube circuits and radio receivers.

The second stage being a combined detector and audio stage is comprised of a further discharge device [3 similar to the first stage comprising a cathode 30, reflecting electrode 29, concentration orcontrol cylinder 28, auxiliary perforated anode 3i, and main anode 32. Numerals 31 and 38 represent potential sources for securing the proper biasing and operating potentials for the cylinder 28 and the anodes 3| and 32, respectively, in a manner similar as shown in connection with the radio frequency amplifier tube In the arrangement shown, the tube l3 acts as a combined diode detector and audio frequency amplifier. For this purpose the signals supplied by the coupling transformer 26 are directly applied to the control cylinder 28 and the plate 29, both acting as a diode rectifier and producing low frequency or demodulated signals. The latter are then applied to the control cylinder 28 by means of a resistance coupling arrangement comprising coupling resistance 35, condenser 34, and leak resistance 36.

In this manner amplified audio frequency signals are produced in the output circuit connected to the auxiilary anode 3| as is well understood. I have also shown a feedback arrangement from the anode 32 to the input of the tube by connecting anode 32 through a feedback coil 33 to a proper positive point on the potential source 38, similar as shown in the input stage l2.

The amplified audio frequency currents set up in the circuit connected to the anode 3! are applied to the output or power tube M by means of a resistance coupling arrangement comprising coupling resistance 39, coupling condenser 40 and leak resistance 4 l The power tube is of similar construction as tubes l2 and 53, comprising a cathode 53, negative reflecting plate 52, controlling cylinder 5|, auxiliary anode 54, and main anode 55. Numerals 50, 56 and 57 represent potential sources for supplying proper biasing and operating potentials for the electrodes, similar as described in connection with stages 12 and I3. It is understood that in place of the separate potential sources, a single source with an associated potentiometer and suitable tap connections may be provided for supplying part or all of the operating biasing potentials required'for the several stages of the receiver in accordance with well known practice in electron tube circuit arrangements.

The output circuit connected to the auxiliary anode 54 includes a translating device such as a loud speaker 58, while the anode 55 is directly connected to a proper positive potential point on the source 51.

Referring to Figure 3, this illustrates a modified type of circuit arrangement utilizing a tube according to the invention showing merely a single stage for simplicity of illustration. According to this circuit, the output circuit is connected to the anode it while the auxiliary anode 19 serves merely as an obstructing or baiiie element for the electron pencil in accordance with the function of applicants discharge device and is directly connected to a proper positive potential point on the source 25. I have furthermore shown the reflecting plate I6 connected to a tap point on the resistance 22 connected in series with the biasing battery 23 for the concentrating cylinder l5 whereby a special biasing battery for the plate It is dispensed with. Numeral II shows a heating battery for the filament ll of the tube.

Referring to Figure 4, this illustrates another circuit for utilizing a tube according to the invention operating according to the push-pull principle. For this purpose the auxiliary anode I9 is divided into two parts, I9 and I9, respectively,

winding 26. The remaining section IQ of the auxiliary anodes is again utilized for regeneration purposes by being connected through a feedback coil 28 to a proper positive point on the potential source 25. Numeral 59 represents a by-pass condenser of well known function in radio receiving circuits. The remaining parts in Figure 4 and their functions substantially correspond to the previous arrangements shown by Figures 2 and 3.

I claim:

1. A signalling circuit comprising an electron discharge device having a cathode and a first anode; a hollow cylindrical control electrode mounted close to said cathode with its axis pointing to said anode; means for applying a negative biasing potential to said control electrode relative to said cathode for concentrating the electron current emitted by said cathode into a pencil striking said anode, a second anode electrode arranged in the path of said electron pencil and having an opening for passing said electron pencil; means including an input circuit for applying potential variations to said control electrode in accordance with input signals; a source of current supply for applying proper positive potentials to said anodes, an output circuit connected to one of said anodes; and a feed-back circuit associated with said input circuit and connected to the remaining anode.

2. A signalling circuit comprising an electron discharge device having a cathode and a first anode; a hollow cylindrical control electrode mounted close to said cathode with its axis pointing to said anode; means for applying a negative biasing potential to said control electrode relative to said cathode for concentrating the electron current emitted by said cathode into a pencil striking said anode; a second anode arranged in front of said first anode and having an opening for passing said electron pencil; means including an input circuit for applying potential variations to said control electrode in accordance with input signals; a source of current supply for applying proper positive potentials to said first and said second anodes, an output circuit connected to said second anode; and a feed-back circuit from said first anode to said input circuit.

3. A circuit arrangement for the amplification of high frequency signal currents comprising an electron discharge device provided with an electron emitter, a main anode, a perforated auxiliary anode positioned between said aforementioned electrodes, means for concentrating the emitted electrons into a beam which passes through the perforated anode and impinges upon the main anode, an input circuit tunable to the high frequency signal currents connected between said concentrating means and the emitter, an output circuit including a source of positive potential connected to said auxiliary anode, said source of positive potential being also connected to the main anode, and a feed back circuit connected to the main anode and coupled to the tunable input circuit.

4. A circuit arrangement for the rectification of high frequency signal currents comprising an electron discharge device provided with an electron emitter, a main anode, a perforated auxiliary anode positioned between said aforementioned electrodes, means for concentrating the emitted electrons into a beam which passes through the perforated anode and impinges upon the main anode, an electrode positioned on that side of the emitter which is remote from the anodes for reflecting the emitted electrons thereto, an input circuit tunable to the high frequency signal currents to be rectified connected between said concentrating means and said reflecting electrode, said concentrating means and reflecting electrode constituting the elements of a diode rectifier, and an output circuit including a source of positive potential connected to said auxiliary anode, said source of positive potential being also connected to the main anode.

5. The circuit as claimed in claim 4:, wherein the main anode has connected to it a feedback circuit which is coupled to the tunable input circuit HENRI FRANCOIS DALPAYRAT. 

